We are investigating the ultrastructure of a hyperthermophilic archaeon, Sulfolobus shibatae, with the hypothesis that the molecular chaperonins in this organism form the basis for a filamentous cytostructure that is a prokaryotic version of the eukaryotic cytoskeleton. The goal is to confirm the presence of filamentous structures previously seen in these organisms and to elucidate their composition; i.e., to establish their relationship to molecular chaperonins. Strategy is to attempt to optimize imaging of cytoplasmic structures using quick-freezing techniques, HR-SEM, and energy-filtering microscopy. Proteins associated with filaments will be identified by immun07gold or fluorescence techniques.